Sound translating device



April 6, 1965 w. HECHT 3,177,301

SOUND TRANSLATING DEVICE Filed June 12. 1961 FIG. 4

INVENTOR. W /AM HECH ATTORNEY United States Patent 3,177,301 SOUND TRANSLATING DEVICE William Hecht, 11 Normandy Terrace, West Orange, NJ. Filed June 12, 1961, Ser. No. 116,599 2 Claims. (Cl. 179-1155) My invention relates generally to sound translating devices, and specifically to a loud speaker of the class in which a cone is supported for driving by a voice coil and magnet. The designation sound translating device includes not only the cone, voice coil, and magnet or any other means for converting electrical energy into sound waves, but also includes the enclosure which supports these members.

An object of my invention is to preserve linearity of response by preventing parasitic vibrations or reflections from being created by any of the parts of the transducer structure.

Another object of my invention is to provide a complete speaker system without any basket support for the cone and the magnet.

A still further object of my invention is to eliminate masking tones resulting from parasitic vibrations or reflections that will suppress or mask other tones.

Yet a further object of my invention is to provide complete acoustical isolation of the front of the cone from the rear of the cone through closely positioned sound absorbing material.

A still further object is to provide a unit construction of great stability, durability and capacity to translate electrical impulses into sound of great purity and fidelity.

These objects and advantages as well as other objects and advantages may be achieved by the device shown, by way of illustration of my invention, in the drawings in which:

FIGURE 1 is an exploded view showing the components of a sound translating device progressively displaced in spaced relation to each other;

FIGURE 2 is a partial vertical sectional view of the assemblage;

FIGURE 3 is a sectional view taken on line 3-3 looking in the direction of the arrows, in FIGURE 1; and

FIGURE 4 is a sectional view taken on the line 4--4 looking in the direction of the arrows, in FIGURE 1.

The human ear is extremely acute in detecting fractional differences in pitch above 2000 c.p.s. Thus, small distortions become glaringly apparent. The human ear hears a constant pitch lower and lower as volume is increased. At lower frequencies, tones just barely loud enough to hear may be 60 db, but at higher frequencies the ear detects tones at a fraction of that volume. Thus music recreated at low volume is deficient in bass notes.

Sound translation devices ideally should have a flat response so that the reproduced tones correspond both in pitch and volume with the original sound. When the product, in addition to corresponding tones, includes noncorresponding tones produced by reflections or parasitic vibrations, these non-corresponding tones may be negligible, imperceptible, and more easily ignored in the lowest range, where the ear is less sensitive to variations in pitch. In the upper ranges however, the ears greater sensitivity does not permit them to be ignored.

But worse, certain types of non-correspondent tones may seize the attention of the ear and cause it to ignore the correspondent tones. Thus, the true tones may be masked by untrue tones after a certain volume level is reached. As a result, a high treble masking tone may completely suppress middle or lower treble ones, and a high bass tone may completely mask lower base tones.

One of the commonest sources of distortion and masking tones is the basket that connects the cone of a speaker with the magnet and voice coil. Light metal baskets produce strong parasitic .vibrations. As the weight and size of the basket is increased, the parasitic vibrations are reduced, but at higher volume never completely vanish. And as the basket is made heavier and its physical dimensions enlarged, reflections between the structure of the basket and the cone are enhanced. A construction that tends to decrease parasitic vibration tends to increase reflections and vice versa.

It has been discovered that a sound translation device can be constructed without a basket. No parasitic vibrations and reflections are created and the tones produced are of such clarity and distinctness, with freedom from parasitic vibration and reflection as to approach in fidelity and live sound which they simulate, no longer limited by the deficiencies of the sound translation device or speaker, but merely by the fidelity of the pick-up or microphone, and the amplifier. The elimination of the basket or direct physical connection of the magnet and voice coil to the cone accomplishes this purality of sound translation.

Referring now to the drawings in detail:

My sound translating device comprises an enclosure 11 having top and bottom walls 12, 13 connected together by opposing side walls 14, 15 and a rear wall. The front of the enclosure is an apertured panel or balfle 16 having a generally circular aperture 17 to which the speaker cone is attached as will be hereinafter set forth. In coincidence with the aperture in the baflle 16 a transverse support 18 is attached to the opposite side walls 14, 15 to serve as a magnet support. This transverse support 18 is provided with a cut out portion 19 sufliciently large to receive the magnet 20. The front of the magnet 20 has a mounting plate 21 by means of which the magnet 20 is mounted on the support 18 by means of screws. The enclosure 11 itself is constructed with the utmost rigidity of non-resonant material and the support 18, in order to provide rigidity, is glued or otherwise set in channels formed in the opposite side walls 14, 15. The magnet 20 has an annular slot of air gap 22 in its top face to receive a portion of a voice coil 23. The voice coil is a tube or base made from a paper to form a base upon which is wound a suitable number of turns of wire 24.

Extending in general perpendicularity to the voice coil 23, a spider 25 is cemented to the base above the windings. The spider is a circular self sustaining fabric web with a plurality of concentric convolutions or corrugations 26. The wires from the ends of the voice coil are secured to the surface of the voice coil base and led toward the outer edge. The peripheral edge of the spider has a generally downwardly extending flange 27 which rests upon the magnet support or the magnet support plate. A small radial flange 28 is formed at the bottom of the downwardly extending flange. With the voice coil 23 in position in the air gap between the magnet and the magnet housing, the voice coil 23 is centered in the air gap of the magnet by the insertion of shims or spacers. Glue is then applied to the small radial flange 28 of the spider 25 and it is secured to the magnet support 18 with the voice coil 23 adjacent to the magnet 20.

A cone 29 is now prepared having a somewhat lesser transverse diameter than the aperture 17 in the baffle 16. It is provided with a surrounding Web or annulus 30 to fill in the gap between the peripheral edge of the cone 29 and the aperture 17 of the baflle 16. The annulus 30 is glued to the edge of the cone 29, so that the annulus bridges the gap between the cone 29 and the aperture 17 in the baflle 16. The leads from the voice coil 23 are introduced through the cone. The inner edge of the cone 29 is of approximately the same diameter as the tubular external diameter of the voice coil 23 and it is so positioned that 'it extends a small distance below the top edge of the voice coil 23 when seated in the bal'lie aperture 17. The outer edge of the annulus 30 is dimensioned to lie in a seat surrounding the cone aperture 17 in the baffle 16 of the enclosure 11. Glue is applied to the aperture or seat 17 in the front wall or battle 16; likewise glue or cement is applied to the top of'the voice coil 23 at the point Where it contacts the bottom of the cone 29. Thus, the bottom of the cone 20 is secured to the voice coil 23 and to the baffle 16 or front wall of the housing 11. The shims which have centered the voice coil 23, not only with respect to the magnet 20, but with respect to the cone 29 may now be removed and the leads from the voice coil connected through the cone to the leads from the input connections, or cross over network. The housing is filled with glass Wool 31 or similar sound absorbent mate rial to approximately one inch of the cone 29. With a basket support of conventional design, this is impossible. A Web of cambric 32 is stapled or otherwise fastened to the cabinet 11 and support 18 in order to retain the glass wool 31 in place and away from the cone yet in close proximity thereto. The glass wool 31 lying in depth behind the cone, can exercise its maximum capacity for deadening or stifling the sound waves emanating from the rear of the cone 29. The front of the cone 29 may then be concealed by applying a suitable ornamental fabric screen over the front wall of the baffle 16. Additional sound translating devices for other frequencies may also be mounted in the other aperture 33 in the front wall of the enclosure 11 so that the full spectrum of audible sound frequencies will be reproduced. If a speaker With a full frequency range is used, the additional speakers are unnecessary. It will be noted that there is no basket or direct connection between the baflie 16 or support 18 as in the conventional sound translating device. Such connection, in the form of a basket, tends to vibrate in sympathy with the cone 29 in spite of the fact that the basket may be made out of heavy metal. No basket is present in the construction described which might introduce parasitic vibrations. Glass Wool 31 can thus be introduced all around the cone and, furthermore, the absence of a rigid structure in the form of the basket in general parallelism with the cone 29, eliminates the possibility of the reflections in the mid-range or high range of audible frequencies. The absence of the supports of the basket eliminates rebound or reflections. These reflections would coact with the normally produced vibrations either to reinforce them or to mitigate them or totally cancel them. Thus, the sound translation would depart from precise reproduction of the original sound if these reflections were present.

t The foregoing description is merely intended to illustrate an embodiment of the invention. The component parts have been shown and described. They each may have substitutes which may perform a substantially similar function; such substitutes may be known as proper substitutes for the said components and may have actually been known or invented before the present invention; these substitutes are contemplated as being within the scope of the appended claims, although they are not specifically catalogued herein.

What is claimed:

1. A sound translating device comprising:

(a) an enclosure having a front wall and a side wall,

(11) the front wall with a cone aperture defining a place for attaching a cone diaphragm,

(c) a cone supported at its outer end by attachment at the edge of the cone aperture,

(d) a voice coil attached at the narrow end of the cone,

(e) a magnet assembly in the enclosure positioned in operable relation to the voice coil,

(f) a sole support for the magnet assembly extending transversely across the enclosure and attached to the sidewall in general parallelism to the front wall,

(g) sound absorbent material in the enclosure covering the support and in spaced relation to the inner sur- 7 face of the cone, (h) an uninterrupted, continuous air column extending from the inner surface of the cone to the sound absorbent material. 2. A sound translating device comprising:

(a) a device according to claim 1 and (b) the support for the magnet assembly positioned in general perpendicularity to the side wall of the enclosure and in general perpendicularity to the axis of the cone.

References Cited by the Examiner UNITED STATES PATENTS ROBERT H. ROSE, Primary Examiner. 

1. A SOUND TRANSLATING DEVICE COMPRISING: (A) AN ENCLOSURE HAVING A FRONT WALL AND A SIDE WALL, (B) THE FRONT WALL WITH A CONE APERTURE DEFINING A PLACE FOR ATTACHING A CONE DIAPHRAGM, (C) A CONE SUPPORTED AT ITS OUTER END BY ATTACHMENT AT THE EDGE OF THE CONE APERTURE, (D) A VOICE COIL ATTACHED AT THE NARROW END OF THE CONE, (E) A MAGNET ASSEMBLY IN THE ENCLOSURE POSITIONED IN OPERABLE RELATION TO THE VOICE COIL, (F) A SOLE SUPPORT FOR THE MAGNET ASSEMBLY EXTENDING TRANSVERSELY ACROSS THE ENCLOSURE AND ATTACHED TO THE SIDE WALL IN GENERALLY PARALLELISM TO THE FRONT WALL, (G) SOUND ABSORBENT MATERIAL IN THE ENCLOSURE COVERING THE SUPPORT AND IN SPACED RELATION TO THE INNER SURFACE OF THE CONE, (H) AN UNINTERRUPTED, CONTINUOUS AIR COLUMN EXTENDING FROM THE INNER SURFACE OF THE CONE TO THE SOUND ABOSRBENT MATERIAL. 